Vehicle communication system and vehicle control device

ABSTRACT

A vehicle communication system includes: a communication server and a vehicle control device. The vehicle control device ( 102 ) includes at least one electronic control unit configured to: recognize a position of the host vehicle; acquire section information on the communication established section and the communication interrupted section; determine in which section, either the communication established section or the communication interrupted section, the host vehicle is traveling or is to travel; perform system driven control of the host vehicle based on the road condition information when the host vehicle travels in the communication established section; and perform driver driven control of the host vehicle when the host vehicle travels in the communication interrupted section.

INCORPORATION BY REFERENCE

The disclosure of Japanese Patent Application No. 2017-026883 filed onFeb. 16, 2017 including the specification, drawings and abstract isincorporated herein by reference in its entirety.

BACKGROUND 1. Technical Field

The present disclosure relates to a vehicle communication system and avehicle control device.

2. Description of Related Art

As a technical document relating to a vehicle communication system,Japanese Patent Application Publication No. 2004-245758 (JP 2004-245758A) is known. This publication describes a system for managing trafficinformation via network communication with vehicles, wherein the trafficinformation on a route on which a first mobile body has passed throughis sent to a second mobile body.

SUMMARY

When executing complicated vehicle control such as autonomous driving,it is desirable to acquire various information, provided by thepreceding vehicle, via network communication. However, in an environmentwhere communication is difficult, the host vehicle cannot acquiresufficient information through communication, which may affect theexecution of vehicle control.

The present disclosure provides a vehicle communication system and avehicle control device capable of executing appropriate vehicle controlaccording to the communication environment of a section in which thehost vehicle travels.

A first aspect of the disclosure provides a vehicle communicationsystem. The vehicle communication system according to the first aspectincludes a communication server configured to communicate road conditioninformation with a plurality of communication vehicles, thecommunication vehicles being vehicles configured to communicate with thecommunication server, the communication server being configured torecognize positions of communicating communication vehicles on a map viacommunication with the communication vehicles, the communicatingcommunication vehicles being the plurality of communication vehicles incommunication with the communication server, and set a communicationestablished section and a communication interrupted section on the map,based on the positions of the communicating communication vehicles onthe map; and a vehicle control device configured to communicate with thecommunication server and configured to perform vehicle control of a hostvehicle using an actuator mounted on the host vehicle, the host vehiclebeing configured to acquire the road condition information from thecommunication server, the vehicle control device including at least oneelectronic control unit configured to recognize a position of the hostvehicle on the map, acquire section information on the communicationestablished section and the communication interrupted section, determinein which section, either the communication established section or thecommunication interrupted section, the host vehicle is traveling or isto travel, based on the position of the host vehicle on the map and thesection information, and perform system driven control of the hostvehicle based on the road condition information when the host vehicletravels in the communication established section, and perform driverdriven control of the host vehicle when the host vehicle travels in thecommunication interrupted section.

According to the vehicle communication system in one aspect of thepresent disclosure, a communication established section and acommunication interrupted section are set on the map based on thepositions of the communicating communication vehicles on the map, thesystem driven control of the host vehicle is performed when the hostvehicle travels in a communication established section and, at the sametime, the driver driven control of the host vehicle is performed whenthe host vehicle travels in a communication interrupted section.Therefore, the vehicle communication system can perform vehicle controlappropriately according to the communication environment of a section inwhich the host vehicle travels.

In the first aspect, the at least one electronic control unit may beconfigured to set, as the communication established section, a sectionin which a communication vehicle of the plurality of communicationvehicles that have continued communication with the communication serverfor a predetermined time or more are traveling, based on the positionsof the communicating communication vehicles on the map, and set, as thecommunication interrupted section, a section in which a certain numberor more of communication vehicles of the plurality of communicationvehicles have communication interrupted, based on the positions of thecommunicating communication vehicles on the map.

In the first aspect, the at least one electronic control unit may beconfigured to set the communication established section, thecommunication interrupted section, and a communication vehicle absencesection on the map based on the positions of the communicatingcommunication vehicles on the map. The at least one electronic controlunit may be configured to acquire the section information on thecommunication established section, the communication interruptedsection, and the communication vehicle absence section that are set onthe map. The at least one electronic control unit may be configured todetermine the host vehicle is traveling or is to travel in which sectionof the communication established section, the communication interruptedsection, or the communication vehicle absence section, based on theposition of the host vehicle on the map and the section information. Theat least one electronic control unit may be configured to perform thedriver driven control when the host vehicle travels in the communicationvehicle absence section.

According to this vehicle communication system, a communication vehicleabsence section is further set on the map based on the positions of thecommunicating communication vehicles on the map and, when the hostvehicle travels in a communication vehicle absence section, the driverdriven control is performed. Therefore, the vehicle communication systemcan perform the vehicle control of the host vehicle appropriatelyconsidering a section in which there is no communication vehicle.

In the first aspect, the at least one electronic control unit may beconfigured to set, as the communication vehicle absence section, asection in which there is no communicating communication vehicle, basedon the positions of the communication vehicles on the map.

In the first aspect, the at least one electronic control unit may beconfigured not to perform the system driven control in the communicationestablished section when a length of the communication establishedsection in which the host vehicle not performing the system drivencontrol travels is equal to or less than a threshold value.

According to this vehicle communication system, the system drivencontrol is not performed if the system driven control can be executedonly for a short period of time and, immediately after the short periodof time, the vehicle control is switched again to the driver drivencontrol. Therefore, the vehicle communication system can avoid thefrequent switching of vehicle control.

In the first aspect, the at least one electronic control unit may beconfigured to release a setting of the communication established sectionwhen a first setting time has elapsed since the communicationestablished section was set on the map, and release a setting of thecommunication interrupted section when a second setting time has elapsedsince the communication interrupted section was set on the map.

According to this vehicle communication system, the setting of acommunication established section of the setting of a communicationinterrupted section is released when a certain time has elapsed,considering that the communication environment of a section varies withthe elapse of time. Therefore, the vehicle communication system canperform vehicle control appropriately according to the actualcommunication environment.

In the first aspect, the first setting time may be 30 seconds or moreand 1 minute or less, and the second setting time may be 30 seconds ormore and 3 minutes or less.

In the first aspect, the at least one electronic control unit may beconfigured to generate a travel plan including candidates of a pluralityof routes on which the host vehicle will travel before arriving at adestination, based on the position of the host vehicle on the map andthe section information.

In the first aspect, the at least one electronic control unit may beconfigured to determine, from the candidates of the routes, a travelingroute on which the host vehicle will travel based on the sectioninformation.

In the first aspect, the at least one electronic control unit may beconfigured to determine, from the candidates of the routes, a routeincluding a maximum number of the communication established section as atraveling route on which the host vehicle will travel, based on thesection information.

In the first aspect, the system driven control may be traveling controlunder which the vehicle control device performs acceleration,deceleration, and steering of the host vehicle autonomously, and thedriver driven control may be traveling control under which the hostvehicle travels based on a driving operation of a driver of the hostvehicle.

The second aspect of the disclosure provides a vehicle control device.The vehicle control device according to the second aspect includes: atleast one electronic control unit configured to recognize a position ofa host vehicle on a map; acquire section information on a communicationestablished section and a communication interrupted section viacommunication with a communication server configured to communicate roadcondition information with a plurality of communication vehicles, thecommunication vehicles being vehicles configured to communicate with thecommunication server, the communication established section and thecommunication interrupted section being set on the map by thecommunication server based on a status of communication with thecommunication vehicles; determine in which section, either thecommunication established section or the communication interruptedsection, the host vehicle is traveling, or is to travel, based on theposition of the host vehicle on the map and the section information;perform vehicle control of the host vehicle using an actuator mounted onthe host vehicle, in such a way that system driven control of the hostvehicle is performed, based on the road condition information acquiredfrom the communication server, when the host vehicle travels in thecommunication established section; and perform driver driven control ofthe host vehicle is performed when the host vehicle travels in thecommunication interrupted section.

According to the vehicle control device in another aspect of the presentdisclosure, the system driven control of the host vehicle is performedwhen the host vehicle travels in a communication established sectionand, at the same time, the driver driven control of the host vehicle isperformed when the host vehicle travels in a communication interruptedsection, using the communication established sections and thecommunication interrupted sections that are set by the communicationserver described above. Therefore, the vehicle control device canperform vehicle control appropriately according to the environment of asection in which the host vehicle travels.

The third aspect of the disclosure provides a vehicle communicationsystem. The vehicle communication system according to the third aspectincludes: a communication server configured to communicate roadcondition information with a plurality of communication vehicles, thecommunication vehicles being vehicles configured to communicate with thecommunication server, the communication server being configured torecognize positions of communicating communication vehicles on a map viacommunication with the communication vehicles, the communicatingcommunication vehicles being the plurality of communication vehicles incommunication with the communication server, and set a communicationestablished section and a communication interrupted section on the map,based on the positions of the communicating communication vehicles onthe map; and a vehicle control device configured to communicate with thecommunication server and configured to perform vehicle control of a hostvehicle using an actuator mounted on the host vehicle, the host vehiclebeing configured to acquire the road condition information from thecommunication server, the vehicle control device including at least oneelectronic control unit configured to recognize a position of the hostvehicle on the map, to acquire section information on the communicationestablished section and the communication interrupted section, todetermine in which section, either the communication established sectionor the communication interrupted section, the host vehicle is traveling,or is to travel, based on the position of the host vehicle on the mapand the section information, to perform a driving assistance when thehost vehicle travels in the communication interrupted section, andperform high-level driving assistance, the high-level driving assistancehaving a higher level of intervention in driving control of the vehiclecontrol device than the driving assistance, based on the road conditioninformation when the host vehicle travels in the communicationestablished section.

As described above, according to the vehicle communication system in oneaspect and the vehicle control device in another aspect of the presentdisclosure, vehicle control can be performed appropriately according tothe communication environment of a section in which the host vehicletravels.

BRIEF DESCRIPTION OF THE DRAWINGS

Features, advantages, and technical and industrial significance ofexemplary embodiments of the disclosure will be described below withreference to the accompanying drawings, in which like numerals denotelike elements, and wherein:

FIG. 1 is a block diagram showing a vehicle communication systemaccording to an embodiment;

FIG. 2 is a diagram showing the setting of sections;

FIG. 3A is a flowchart showing the setting processing of a communicationestablished section and a communication vehicle absence section;

FIG. 3B is a flowchart showing the setting processing of a communicationinterrupted section;

FIG. 4A is a flowchart showing the release processing of a communicationestablished section;

FIG. 4B is a flowchart showing the release processing of a communicationinterrupted section;

FIG. 5 is a flowchart showing vehicle control performed by a vehiclecontrol device; and

FIG. 6 is a flowchart showing the vehicle control switching restrictionprocessing.

DETAILED DESCRIPTION OF EMBODIMENTS

Embodiments of the present disclosure will be described below withreference to the drawings.

[Configuration of Vehicle Communication System]

FIG. 1 is a block diagram showing a vehicle communication systemaccording to an embodiment. A vehicle communication system 100 shown inFIG. 1 is a system that includes a communication server 101 and avehicle control device 102.

<Configuration of Communication Server>

First, the communication server 101 will be described. The communicationserver 101, provided in facilities such as an information managementcenter, communicates with a plurality of communication vehicles. Acommunication vehicle is a vehicle having the function to communicatewith the communication server 101. In general, a communication vehiclehas the function to recognize the position of the vehicle on the map andthe function to recognize road conditions outside the vehicle.

The communication server 101 is configured as a general computer thatincludes a CPU, a storage unit, and a communication control unit. Thestorage unit may be a ROM and/or a RAM, or may be a storage medium suchas an HDD configured as a Redundant Array Soft Inexpensive Disks (RAID)configuration. The storage unit may be provided outside thecommunication server 101. The communication control unit is acommunication device such as a network card that controls communication.Each function of the communication server 101 is realized by acombination of the operations of the hardware devices described above.The communication server 101 may be configured by a plurality ofcomputers. The communication server 101 may be a cloud server.

The communication server 101 is connected to a server side communicationunit 15 that is provided for communication with the host vehicle(vehicle control device 102). The server side communication unit 15 is,for example, the communication facilities of the center where thecommunication server 101 is provided.

The communication server 101 includes a communication vehicle positionrecognition unit 11, a road condition information acquisition unit 12, asection setting unit 13, and a server side map database 14.

The communication vehicle position recognition unit 11 recognizes thepositions of communication vehicles on the map via communication with aplurality of communication vehicles. For example, the communicationvehicle position recognition unit 11 recognizes the positions of thecommunication vehicles on the map by acquiring the information on thepositions on the map (such as GPS information), recognized by each ofthe communication vehicles, from a plurality of communication vehicles.

The road condition information acquisition unit 12 acquires the roadcondition information, which is the information on the road conditionrecognized by each of the communication vehicles, via communication witha plurality of communication vehicles. Examples of road conditionsinclude the conditions of obstacles on the road on which thecommunication vehicle travels (conditions of moving obstacles such asother vehicles, bicycles, and pedestrians, and conditions of stationaryobstacles such as utility poles, guardrails, and buildings). The roadcondition information acquisition unit 12 acquires the road conditioninformation in association with the information on the positions of thecommunication vehicles on the map. The communication server 101 providesvarious information, such as the road condition information, to acommunication vehicle in response to a request.

The section setting unit 13 sets a communication established section, acommunication interrupted section, and a communication vehicle absencesection on the map, based on the status of communication between acommunication vehicle and the communication server 101. Morespecifically, the section setting unit 13 sets a communicationestablished section, a communication interrupted section, and acommunication vehicle absence section, based on the positions of thecommunication vehicles on the map recognized by the communicationvehicle position recognition unit 11. A communication establishedsection is a section where communication between the communicationserver 101 and a communication vehicle is established. A communicationvehicle absence section is a section where there is no communicationvehicle. A communication interrupted section is a section wherecommunication between the communication server 101 and a communicationvehicle is interrupted. Communication interrupted sections include asection where the communication server 101 and the host vehicle cannotcommunicate because of a structural reason (a canyon of buildings, atunnel, and an underground parking lot) and a section where thecommunication is temporarily interrupted (the influence of the weather(thunderstorms etc.), the influence of radio disturbances due to thetesting of radio wave test equipment, or the operation of a powerplant).

A communication established section, a communication interruptedsection, and a communication vehicle absence section may be setseparately for each lane, or may be set for a road withoutdistinguishing lanes. In addition, a communication established section,a communication interrupted section, and a communication vehicle absencesection may be distinguished by Level of Service [LOS] labels. Forexample, a communication established section may be assigned a LOS label3, a communication vehicle absence section may be assigned a LOS label2, and a communication interrupted section may be assigned a LOS label1.

The section setting unit 13 sets a communication established sectionbased on the position of a communication vehicle on the map when thecommunication vehicle is in communication with the communication server101. For example, when the communication between the communicationserver 101 and a communication vehicle continues for a predeterminedtime or more, the section setting unit 13 sets the section, where thecommunication vehicle in communication with the communication server 101travels, as a communication established section. A communicationestablished section may be set as a section that crosses an intersectionor a branch road.

The section setting unit 13 sets a section as a communication vehicleabsence section if there is no communicating communication vehicle,based on the positions of the communication vehicles on the map that arein communication with the communication server 101. The section settingunit 13 does not necessarily have to set a communication vehicle absencesection.

The section setting unit 13 sets a communication interrupted sectionbased on the interruption of communication, and the restoration ofcommunication, of communication vehicles. If a communication vehicleabsence section is set, the section setting unit 13 overwrites acommunication interrupted section on the communication vehicle absencesection. The section setting unit 13 recognizes a communicationinterruption point (the start point of a communication interruptedsection) based on the recognition result of the communication vehicleposition recognition unit 11. The interruption point described above isa point where the communication of a certain number or more ofcommunication vehicles is interrupted. The section setting unit 13 mayrecognize a point where a certain number or more of communicationvehicles have the communication interrupted within a predetermined timeas the communication interruption point, considering an elapse of time.

The certain number of communication vehicles may be a fixed number ormay be a number different depending on the shape of the road (forexample, depending on whether the road is a double-lane road or asingle-lane road). It is not necessary to include the same vehicle inthe certain number of communication vehicles. The predetermined time maybe a fixed value or may be different depending on the shape of the road(for example, depending on whether the road is a double-lane road or asingle-lane road).

The section setting unit 13 recognizes a communication restoration point(the end point of a communication interrupted section) based on therecognition result of the communication vehicle position recognitionunit 11. The communication restoration point described above is a pointwhere the communication is restored between a certain number of more ofcommunication vehicles that have the communication interrupted at thesame communication interruption point and the communication server 101.The certain number or more of communication vehicles do not need to bethe same as the communication vehicles used when recognizing thecommunication interruption point. The section setting unit 13 mayrecognize a point where a certain number or more of communicationvehicles have the communication interrupted within a predetermined timeas the communication interruption point.

The section setting unit 13 sets the section between a communicationinterruption point and a communication restoration point as acommunication interrupted section. The section setting unit 13overwrites a communication vehicle absence section with a communicationinterrupted section. When a communication interruption point and acommunication restoration point are recognized on the same road, thesection setting unit 13 may set the section between these points as acommunication interrupted section. The section setting unit 13 may set acommunication interrupted section across an intersection or a branch. Inthis case, the section setting unit 13 recognizes a plurality ofcommunication restoration points for one communication interruptionpoint. That is, in this case, the communication interrupted section mayhave multiple exits for one entrance. The method for setting acommunication interrupted section is not limited to the method describedabove.

When the setting of a communication established section and the settingof a communication interrupted section overlap, the section setting unit13 treats the overlapping section as a communication establishedsection. For a section where the setting of a communication establishedsection and the setting of a communication interrupted section overlap,the section setting unit 13 may store the traveling trajectory of acommunication vehicle with which communication has been established.

FIG. 2 is a diagram showing the setting of sections. FIG. 2 shows thehost vehicle M, the center C, route A, route B, route C, communicationvehicles N1 to N4, and the destination G. The host vehicle M is avehicle that is controlled by the vehicle control device 102 of thevehicle communication system 100. The center C is facilities where thecommunication server 101 is installed. Communication vehicles N1 and N2are vehicles communicating with the communication server 101 of thecenter C. Communication vehicles N1 and N2 are traveling on route A.Communication vehicles N3 and N4 are vehicles in the state in whichcommunication with the communication server 101 of the center C isinterrupted. Communication vehicles N3 and N4 are traveling on route B.There is no communication vehicle on route C.

In the situation shown in FIG. 2, the section setting unit 13 sets acommunication established section on route A based on the positions ofthe communication vehicles N1 and N2 on the map that are communicatingwith the communication server 101. For example, the section setting unit13 sets the section in which communication vehicles N1 and N2, whichhave been communicating with the communication server 101 for apredetermined time or more, are traveling as a communication establishedsection. The section setting unit 13 sets route C, where there is nocommunication vehicle that is communicating with the communicationserver 101, as a communication vehicle absence section.

In addition, the section setting unit 13 recognizes the communicationinterrupted section on route B based on the communication interruptionand the communication restoration of the communication vehicles N3 andN4. The section setting unit 13 recognizes the communicationinterruption point b1, at which the communication between thecommunication vehicles (N3 and N4) and the communication server 101 isinterrupted, and the communication restoration point b2 at which thecommunication between the communication vehicles (N3 and N4) and thecommunication server 101 is restored. The section setting unit 13recognizes the section between the communication interruption point b1and the communication restoration point b2 as the communicationinterrupted section.

Next, the release of section setting will be described. The sectionsetting unit 13 counts the elapsed time since a communicationestablished section was set on the map. The section setting unit 13counts the elapsed time based on the timer of the communication server101. The section setting unit 13 releases the setting of thecommunication established section when the first setting time haselapsed since the communication established section was set. The firstsetting time is a time that is set in advance (for example, 30 seconds).The first setting time can be set to a time of 30 seconds or more and 1minute or less.

Similarly, the section setting unit 13 counts the elapsed time since acommunication interrupted section was set on the map. The sectionsetting unit 13 counts the elapsed time based on the timer of thecommunication server 101. The section setting unit 13 releases thesetting of the communication interrupted section when the second settingtime has elapsed since the communication interrupted section was set.The second setting time is a time that is set in advance (for example,30 seconds). The second setting time can be set to a time of 30 secondsor more and 3 minutes or less. The second setting time may be longerthan the first setting time. By doing so, it is possible to easilyrelease the setting of a communication interrupted section and avoidadverse effect on vehicle control.

After the setting of a communication established section or acommunication interrupted section is released, the section setting unit13 may set the setting-released section as a communication vehicleabsence section if the setting of a communication established section ora communication interrupted section is not overwritten in thesetting-released section.

The server side map database 14 is a database that stores mapinformation. The server side map database 14 is a database that is usedas the reference of the vehicle side map database 25 that will bedescribed later. The server side map database 14 keeps the mapinformation up-to-date by a known technique via communication with acommunication vehicle such as a probe car.

The server side map database 14 stores the section information on acommunication established section, a communication interrupted section,and a communication vehicle absence section that are set by the sectionsetting unit 13. The section information may be stored in a databasedifferent from the server side map database 14.

<Configuration of Vehicle Control Device>

Next, the vehicle control device 102 will be described. The vehiclecontrol device 102 is a device that performs the vehicle control of thehost vehicle. The host vehicle may be a vehicle that functions as acommunication vehicle described above or may be a vehicle that does notfunction as a communication vehicle. That is, the host vehicle does notnecessarily have to be a device that provides information to thecommunication server 101. The vehicle control includes at least twotypes of control: system driven control and driver driven control. Thevehicle control device 102 recognizes a request for starting the systemdriven control in response to a driver's operation. When the conditionthat is set by the driver in advance is satisfied, the vehicle controldevice 102 may automatically start the system driven control.

The system driven control is the traveling control of the host vehiclewhen the traveling is controlled mainly by the vehicle control device102. The system driven control is, for example, autonomous drivingcontrol. The autonomous driving control is control in which the hostvehicle travels autonomously without the driver performing the drivingoperation. The system driven control may be thought of as controlcorresponding to the so-called autonomous driving level 3 or autonomousdriving level 4. In the system driven control, the vehicle controldevice 102 controls the acceleration, deceleration, and steering of thehost vehicle.

The driver-driven control is the traveling control of the host vehiclewhen the host vehicle is driven mainly by the driver. The driver-drivencontrol is provided, for example, in the form of driving assistancecontrol, guidance control provided to the driver, and alerting controlprovided to the driver. The driving assistance control refers to thecontrol provided to assist the driver in traveling of the host vehiclewhile the host vehicle is driven mainly by the driver's manual drivingoperation. The driving assistance control may include Lane KeepingAssist [LKA] and/or Adaptive Cruise Control [ACC]. The drivingassistance control may be thought of as the control corresponding to theautonomous driving level 1 or autonomous driving level 2.

The vehicle control device 102 includes an Electronic Control Unit (ECU)10 that integrally manages the device. The ECU 30 is an electroniccontrol unit that includes a Central Processing Unit (CPU), a Read OnlyMemory (ROM), a Random Access Memory (RAM), and a Controller AreaNetwork (CAN) communication circuit. The ECU 30 loads a program storedin the ROM into the RAM and causes the CPU to execute the program loadedinto the RAM to implement various functions. The ECU 30 may beconfigured by a plurality of electronic control units.

The ECU 30 is connected to a GPS receiver 21, an external sensor 22, aninternal sensor 23, a driving operation detection unit 24, a vehicleside map database 25, a Human Machine Interface [HMI] 26, an actuator27, and a vehicle side communication unit 28.

The GPS receiver 21 receives signals from three or more GPS satellitesto measure the position of the host vehicle (for example, the latitudeand longitude of the host vehicle). The GPS receiver 21 sends themeasured position information on the host vehicle to the ECU 30.

The external sensor 22 is a detection apparatus for detecting thesurrounding situation of the host vehicle. The external sensor 22includes at least one of a camera and a radar sensor.

The camera is a capturing apparatus that captures the external situationof the host vehicle. The camera is provided on the interior side of thewindshield of the host vehicle. The camera sends the capturedinformation on the external situation of the host vehicle to the ECU 30.The camera may be a monocular camera or a stereo camera. The stereocamera includes two capturing units arranged so that the disparitybetween the right eye and the left eye is reproduced. The informationcaptured by the stereo camera also includes the depth directioninformation.

The radar sensor is a detection apparatus that detects an obstaclearound the host vehicle using radio waves (for example, millimeterwaves) or light. The radar sensor includes a millimeter radar or a LightDetection and Ranging (LIDAR). The radar sensor detects an obstacle bysending radio waves or light to the surroundings of the host vehicle andby receiving radio waves or light reflected by the obstacle. The radarsensor sends the detected obstacle information to the ECU 30. Obstaclesinclude stationary obstacles such as guardrails and buildings as well asmoving obstacles such as pedestrians, bicycles, and other vehicles.

The internal sensor 23 is a detection apparatus that detects thetraveling state of the host vehicle. The internal sensor 23 includes avehicle speed sensor, an acceleration sensor, and a yaw rate sensor. Thevehicle speed sensor is a detection apparatus that detects the speed ofthe host vehicle. An example of the vehicle speed sensor is a wheelspeed sensor that is provided on the wheels of the host vehicle or onthe drive shaft that rotates in synchronization with the wheels todetect the rotation speed of the wheels. The vehicle speed sensor sendsthe detected vehicle speed information (wheel speed information) to theECU 30.

The acceleration sensor is a detection apparatus that detects theacceleration of the host vehicle. The acceleration sensor includes alongitudinal acceleration sensor that detects acceleration in thelongitudinal direction of the host vehicle and a lateral accelerationsensor that detects the lateral acceleration of the host vehicle. Theacceleration sensor sends the acceleration information on the hostvehicle to the ECU 30. The yaw rate sensor is a detection apparatus thatdetects the yaw rate (turning angle velocity) around the vertical axisat the center of gravity of the host vehicle. A gyro sensor may be usedas the yaw rate sensor. The yaw rate sensor sends the detected yaw rateinformation on the host vehicle to the ECU 300.

The driving operation detection unit 24 detects the driver's drivingoperation. The driving operation detection unit 24 includes anaccelerator pedal sensor, a brake pedal sensor, and a steering sensor.The driving operation detection unit 24 sends the detected driver'sdriving operation to the ECU 30.

The vehicle side map database 25 is a database that stores the mapinformation. The vehicle side map database 25 is formed, for example, inthe Hard Disk Drive [HDD] mounted on the host vehicle. The mapinformation includes the position information on roads, the informationon road shapes (for example, whether the road is a curved road or astraight road, the curvature of a curved road, and so on), the positioninformation on intersections and branch points, the position informationon structures, and so on. The map information includes the sectioninformation on the sections that are set on the map in advance. Thevehicle side map database 25 carries out communication with thecommunication server 101 to update the map information as necessary withthe server side map database 14 as its reference database. The vehicleside map database 25 may be provided in a server capable ofcommunicating with the host vehicle.

The HMI 26 is an interface for outputting and inputting informationbetween the driver and the vehicle control device 102. The HMI 26 has adisplay for displaying image information to the driver and operationbuttons or a touch panel for allowing the driver to perform inputoperations. The HMI 26 sends the information received from the driver tothe ECU 30. The HMI 26 displays image information on the display inresponse to the control signal from the ECU 30.

The actuator 27 is an apparatus used for controlling the host vehicle.The actuator 27 includes at least a throttle actuator, a brake actuator,and a steering actuator. The throttle actuator controls the amount ofair to be supplied to the engine (throttle angle) according to thecontrol signal from the ECU 30 to control the driving force of the hostvehicle. When the host vehicle is a hybrid vehicle, the amount of air tobe supplied to the engine is input to the engine and, in addition, thecontrol signal from the ECU 30 is input to the motor, which works as thepower source, to control the driving force. When the host vehicle is anelectric vehicle, the control signal from the ECU 30 is input to themotor, which works as the power source, to control the driving force.The motor that works as power sources in these cases constitutes theactuator 27.

The brake actuator controls the brake system according to the controlsignal, received from the ECU 30, to control the braking force to beapplied to the wheels of the host vehicle. As the brake system, ahydraulic brake system may be used. The steering actuator controls thedriving of the assist motor, one component of the electric powersteering system for controlling the steering torque, according to thecontrol signal received from the ECU 30. By doing so, the steeringactuator controls the steering torque of the host vehicle.

The vehicle side communication unit 28 is an apparatus for communicatingwith the communication server 101. The vehicle control device 102 sendsand receives various information to and from the communication server101 via the vehicle side communication unit 28. The communication formatis not limited to a particular format.

Next, the functional configuration of the ECU 30 will be described. TheECU 30 includes a vehicle position recognition unit 31, a road conditionrecognition unit 32, a traveling state recognition unit 33, a sectioninformation acquisition unit 34, a travel plan generation unit 35, asection determination unit 36, and a vehicle control unit 37. Thefunctions of the ECU 30 described below may also be executed, in part,by a server capable of communicating with the host vehicle.

The vehicle position recognition unit 31 recognizes the position of thehost vehicle on the map based on the position information, received bythe GPS receiver 21, and the map information stored in the vehicle sidemap database 25. In addition, the vehicle position recognition unit 31recognizes the position of the host vehicle by the SimultaneousLocalization and Mapping [SLAM] technology, using the positioninformation on stationary obstacles, such as utility poles, included inthe map information stored in the vehicle side map database 25 and thedetection result detected by the external sensor 22. The vehicleposition recognition unit 31 may recognize the position of the hostvehicle on the map using other known methods.

The road condition recognition unit 32 recognizes the road condition ofthe road on which host vehicle is traveling, based on the detectionresult detected by the external sensor 22. The road conditions includethe condition of obstacles on the road on which the host vehicle istraveling (moving obstacles such as other vehicles, bicycles, andpedestrians, and stationary obstacles such as utility poles, guardrails,and buildings). The road condition recognition unit 32 recognizes theroad condition by a known method based on the image captured by thecamera and the obstacle information sensed by the radar sensor.

The traveling state recognition unit 33 recognizes the traveling stateof the host vehicle based on the detection result detected by theinternal sensor 23. The traveling state includes the vehicle speed ofthe host vehicle, the acceleration of the host vehicle, and the yaw rateof the host vehicle. More specifically, the traveling state recognitionunit 33 recognizes the vehicle speed of the host vehicle based on thevehicle speed information sensed by the vehicle speed sensor. Thetraveling state recognition unit 33 recognizes the acceleration of thehost vehicle based on the acceleration information sensed by theacceleration sensor. The traveling state recognition unit 33 recognizesthe direction of the host vehicle based on the yaw rate informationsensed by the yaw rate sensor.

The section information acquisition unit 34 acquires the sectioninformation that is set by the section setting unit 13 via communicationwith the communication server 101. When the target route of the hostvehicle is already set, the section information acquisition unit 34 mayacquire only the section information on the sections that are located onthe target route and/or near to the target route. The sectioninformation acquisition unit 34 recognizes the communication establishedsections, communication interrupted sections, and communication vehicleabsence sections that are set on the map, based on the sectioninformation.

The travel plan generation unit 35 generates a travel plan for causingthe host vehicle to travel, by the system driven control, toward thedestination that is set by the driver in advance. When the destinationis set, the travel plan generation unit 35 searches for a target routefor the host vehicle to arrive at the destination, based on the positionof the host vehicle on the map and the map information. When there is aplurality of target route candidates leading to the destination, thetravel plan generation unit 35 searches for a target route that includesonly communication established sections before arriving at thedestination, based on the section information acquired by the sectioninformation acquisition unit 34. If there is no target route thatincludes only communication established sections before arriving at thedestination, the travel plan generation unit 35 may search for a targetroute that includes communication vehicle absence sections and/orcommunication interrupted sections. In this case, the travel plangeneration unit 35 uses a target route that is one of the plurality oftarget route candidates and that has the highest ratio of communicationestablished sections.

The travel plan generation unit 35 may acquire the road conditioninformation (information on the road conditions the communicationvehicles provided to the communication server 101) via communicationwith the communication server 101 and, using the acquired road conditioninformation, search for a target route with fewer obstacles.

When a target route is used, the travel plan generation unit 35 acquiresthe road condition information on the target route via communicationwith the communication server 101. The travel plan generation unit 35generates a travel plan for use by the system driven control, based onthe target route, the map information, the road condition information,the road condition around the host vehicle recognized by the roadcondition recognition unit 32, and the traveling state of the hostvehicle recognized by the traveling state recognition unit 33.

For example, a travel plan includes the control target value of the hostvehicle for a position on the target route of the host vehicle. Thepositions on the target route are positions in the extending directionof the target route on the map. The positions on the target route meanset longitudinal positions that are set at predetermined intervals (forexample, at one-meter intervals) in the extending direction of thetarget route. The control target value is the value of a control targetof the vehicle used in the travel plan. The control target value is setin association with each set longitudinal position on the target route.The travel plan generation unit 35 generates a travel plan by settingthe set longitudinal positions at predetermined intervals on the targetroute and, at the same time, setting the control target value (forexample, the target lateral position and the target vehicle speed) foreach set longitudinal position. The set longitudinal position and thetarget lateral position may be set by combining into one set ofpositional coordinates. The set longitudinal position and the targetlateral position mean the longitudinal position information and thelateral position information that are set as a target in the travelplan.

The method of generating a travel plan and the contents of a travel planare not limited to those described above. The travel plan generationunit 35 may generate a travel plan appropriate for executing the systemdriven control by using the road condition information acquired viacommunication with the communication server 101.

The section determination unit 36 determines whether the host vehicle istraveling in a communication established section, based on the positionof the host vehicle on the map and the section information. In addition,the section determination unit 36 determines whether the host vehicle istraveling in a communication interrupted section, based on the positionof the host vehicle on the map and the section information. Similarly,the section determination unit 36 determines whether the host vehicle istraveling in a communication vehicle absence section, based on theposition of the host vehicle on the map and the section information.

The vehicle control unit 37 performs the vehicle control of the hostvehicle. The vehicle control unit 37 performs the vehicle control bysending the control signal to the actuator 27. If the start of thesystem driven control is requested by the operation of the driver and ifit is determined by the section determination unit 36 that the hostvehicle is traveling in a communication established section, the vehiclecontrol unit 37 performs the system driven control of the host vehicle.The vehicle control unit 37 performs the system driven control of thehost vehicle based on the map information, the position of the hostvehicle on the map, the road conditions around the host vehicle, thetraveling sate of the host vehicle, the road condition informationacquired via communication with the communication server 101, and thetravel plan generated by the travel plan generation unit 35.

If it is determined that the host vehicle is traveling in acommunication established section but if the communication between thehost vehicle and the communication server 101 is interrupted for apredetermined time or more, the vehicle control unit 37 may terminatethe system driven control and switch the control to the driver drivencontrol.

If the start of the system driven control is requested but if it isdetermined by the section determination unit 36 that the host vehicle istraveling in a communication interrupted section, the vehicle controlunit 37 does not perform the system driven control of host vehicle butperforms the driver driven control of the host vehicle because thecommunication between the communication server 101 and the host vehicleis interrupted.

The vehicle control unit 37 performs the driver driven control (forexample, driving assistance control that is known) based on the drivingoperation of the driver, the road condition around the host vehicle, andthe traveling state of the host vehicle.

In other words, when the host vehicle is traveling in a communicationinterrupted section, the vehicle control unit 37 uses a vehicle controlassistance level lower than that used when the host vehicle is travelingin a communication established section. For example, the vehicle controlunit 37 switches the control from the system driven control,corresponding to the autonomous driving level 3, to the driver drivencontrol corresponding to the autonomous driving level 2.

Similarly, if the start of the system driven control is requested but ifit is determined by the section determination unit 36 that the hostvehicle is traveling in a communication vehicle absence section, thevehicle control unit 37 performs the driver driven control of the hostvehicle.

In addition, if the length of the communication established section inwhich the host vehicle not performing the system driven control istraveling (that is, the host vehicle is traveling under the driverdriven control or in the manual operation mode) is equal to or smallerthan the set threshold, the vehicle control unit 37 does not perform thesystem driven control in that communication established section. The setthreshold value is a value that is set in advance. The set thresholdvalue may be a fixed value or may be a value that is changed accordingto the vehicle speed of the host vehicle, traffic jam condition, and soon. The vehicle control unit 37 may set the set threshold to a smallervalue as the density of other vehicles (for example, the number of othervehicles per unit distance) in the communication established section, inwhich the host vehicle is traveling or is to travel, is higher. When atarget route is set, the length of the communication established sectionto be compared with the set threshold may be the length of thecommunication established section on the target route (that is, when thetarget route branches off into an alleyway in the middle of thecommunication established section, the length of the communicationestablished section is the length from the entrance of the communicationestablished section to the branch point).

Before switching from the system driven control to the driver drivencontrol, the vehicle control unit 37 notifies (alerts) the driver viathe HMI 26 that the control will be switched to the driver drivencontrol. The HMI 26 notifies the driver that the control will beswitched to driver driven control by an image display on the displayand/or an audio output from the speaker. When the control can beswitched from the driver driven control to the system driven control(that is, when the host vehicle under the driver driven control enters acommunication established section), the vehicle control unit 37 maysuggest the driver that the control should be switched to the systemdriven control. If the driver permits the switching to the system drivencontrol, the vehicle control unit 37 switches the control from driverdriven control to system driven control. If the driver has set, inadvance, the automatic switching to the system driven control, thevehicle control unit 37 may notify the driver that the control will beswitched from the driver driven control to the system driven controland, then, switch the control from the driver driven control to thesystem driven control.

In addition, while the driver driven control (or manual driving) of thehost vehicle is performed, the vehicle control device 102 may search fora route that includes a communication established section based on thelatest section information and, if such a route is found, may proposethat the target route be changed. For example, in FIG. 2, assume thatthe vehicle control device 102 provides the driver with the guidanceinformation notifying the driver that the route including route B is thetarget route to the destination G. In this case, based on the latestsection information, the travel plan generation unit 35 recognizes routeA that is parallel to route B composed of the communication interruptedsection and that includes the communication established section. Uponrecognizing route A that is different from the target route and that iscomposed of the communication established section, the travel plangeneration unit 35 proposes the driver, via the HMI 26, that the targetroute be changed to a new target route that includes route A (that is,proposes that the system driven control be performed by changing thetarget route). When the driver permits the change, the travel plangeneration unit 35 changes the target route to the route that includesroute A. The vehicle control unit 37 performs the system driven controlif it is determined that the host vehicle is to travel in thecommunication established section.

If a communication established section, a communication interruptedsection, and a communication vehicle absence section are set on a roadbasis and, on a multiple-lane road, if there is a section in which acommunication established section and a communication interruptedsection overlap, the vehicle control device 102 may propose the driverthat the host vehicle should travel in the lane in which a communicationvehicle that has successfully established the communication hastraveled. The vehicle control unit 37 performs the system driven controlif it is determined that the host vehicle is to travel in acommunication established section.

In addition, if a communication established section, a communicationinterrupted section, and a communication vehicle absence section are seton a lane basis, the vehicle control device 102 may propose the driverthat the lane be changed so that the host vehicle travels in thecommunication established section. More specifically, if it isrecognized that there is a communication interrupted section (orcommunication vehicle absence section) in the traveling lane in whichthe host vehicle travels and that there is a communication establishedsection in the lane adjacent to the traveling lane, the travel plangeneration unit 35 proposes the driver that the lane be changed to thelane in the communication established section. If it is determined, as aresult of a lane change, that the host vehicle is to travel in thecommunication established section, the vehicle control unit 37 performsthe system driven control. Another mode is also possible in which, whenthe driver permits the change, the vehicle control unit 37 automaticallychanges the lane to a lane in the communication established section.

If it is recognized, during the execution of the system driven controlof the host vehicle, that a communication interrupted section is newlyset on the target route of a travel plan based on the latest sectioninformation, the vehicle control device 102 may propose the driver tochange the route. For example, in FIG. 2, assume that the host vehicle Mhas a travel plan according to which the host vehicle will pass throughroute B. At this time, if it is recognized that a communicationinterrupted section is newly set in route B based on the latest sectioninformation, the travel plan generation unit 35 re-searches for a targetroute. If route A composed of a communication established section issearched for as a result of the re-search, the travel plan generationunit 35 proposes the driver, via the HMI 26, that the target route bechanged to the route that includes route A. For continued execution ofthe system driven control, the travel plan generation unit 35 proposesthe driver that the target route be changed to the route that includesroute A. The travel plan generation unit 35 changes the target route tothe route including route A when the driver permits the change. Thevehicle control unit 37 changes the target route to the route includingroute A and continues the system driven control.

In addition, if it is determined, during the execution of the systemdriven control of the host vehicle, that the host vehicle is travelingin a section where a communication established section and acommunication interrupted section overlap (that is, if it is determinedthat the host vehicle is traveling in a communication establishedsection and, at the same time, in a communication interrupted section),the vehicle control unit 37 may perform the system driven control sothat the host vehicle travels along the traveling trajectory of acommunication vehicle that successfully performed the communication withthe communication server 101. In some cases, a position where thecommunication between the communication server 101 and the host vehicleis interrupted and a position where the communication between them isestablished are mixed even on the same road (or in the same lane).Therefore, if it is determined that the host vehicle is traveling in asection where a communication established section and a communicationinterrupted section overlap, the vehicle control unit 37 can cause thehost vehicle to travel along the traveling trajectory of a communicationvehicle that is determined to have established the communication withthe communication server 101, thus avoiding an interruption in thecommunication.

[Processing of Vehicle Communication System]

The processing of the vehicle communication system 100 according to thepresent embodiment will be described below.

<Setting Processing of a Communication Established Section and aCommunication Vehicle Absence Section>

FIG. 3A is a flowchart showing the setting processing of a communicationestablished section and a communication vehicle absence section. Theflowchart shown in FIG. 3A is executed as necessary in the communicationserver 101.

In S10, the communication server 101 uses the communication vehicleposition recognition unit 11 to recognize the positions of thecommunication vehicles on the map as shown in FIG. 3A. The communicationvehicle position recognition unit 11 communicates with a plurality ofcommunication vehicles to recognize the positions of the communicationvehicles on the map. After that, the processing of the communicationserver 101 proceeds to S12.

In S12, the communication server 101 uses the section setting unit 13 todetermine whether the communication between the communication server 101and the communication vehicles has continued for a predetermined time ormore. If it is not determined that the communication with thecommunication vehicles has continued for a predetermined time or more(S12: NO), the communication server 101 terminates the currentprocessing. If it is determined that the communication with thecommunication vehicles has continued for a predetermined time or more(S12: YES), the processing of the communication server 101 proceeds toS14.

In S14, the communication server 101 uses the section setting unit 13 toset a communication established section and a communication vehicleabsence section. For example, the section setting unit 13 sets a sectionin which the communication vehicles that continue communication with thecommunication server 101 are traveling as a communication establishedsection. The section setting unit 13 sets a section in which there is nocommunication vehicle that is communicating with the communicationserver 101 as a communication vehicle absence section. After that, thecommunication server 101 terminates the current processing.

<Setting Processing of a Communication Interrupted Section>

FIG. 3B is a flowchart showing the setting processing of a communicationinterrupted section. The flowchart shown in FIG. 3B is executed asnecessary in the communication server 101.

In S20, the communication server 101 uses the communication vehicleposition recognition unit 11 to recognize the positions of thecommunication vehicles on the map as shown in FIG. 3B. The communicationvehicle position recognition unit 11 communicates with a plurality ofcommunication vehicles to recognize the positions of the communicationvehicles on the map. After that, the processing of the communicationserver 101 proceeds to S22.

In S22, the communication server 101 uses the section setting unit 13 todetermine whether a communication interruption point is recognized. Thecommunication interruption point is a point where the communication of acertain number or more of communication vehicles is interrupted. If itis not determined that the communication interruption point, where thecommunication of a certain number or more of communication vehicles isinterrupted, is recognized (S22: NO), the communication server 101terminates the current processing. If it is determined that thecommunication interruption point, where the communication of a certainnumber or more of communication vehicles is interrupted, is recognized(S22: YES), the processing of the communication server 101 proceeds toS24.

In S24, the communication server 101 uses the section setting unit 13 todetermine whether a communication restoration point is recognized. Thecommunication restoration point is a point where the communication of acertain number or more of communication vehicles whose communication wasinterrupted at the same communication interruption point is restored. Ifit is not determined that the communication restoration point, where thecommunication of a certain number or more of communication vehicles isrestored, is recognized (S24: NO), the communication server 101terminates the current processing. If it is determined that thecommunication restoration point, where the communication of a certainnumber or more of communication vehicles is restored, is recognized(S24: YES), the processing of the communication server 101 proceeds toS26.

In S26, the communication server 101 uses the section setting unit 13 toset a communication interrupted section. The section setting unit 13sets the section between the communication interruption point and thecommunication restoration point as a communication interrupted section.After that, the communication server 101 terminates the currentprocessing.

<Release Processing of a Communication Established Section>

FIG. 4A is a flowchart showing the release processing of a communicationestablished section. The flowchart shown in FIG. 4A is executed when acommunication established section was set.

In S30, the communication server 101 uses the section setting unit 13 todetermine whether the first setting time has elapsed since thecommunication established section was set, as shown in FIG. 4A. If it isnot determined that the first setting time has elapsed since thecommunication established section was set (S30: NO), the communicationserver 101 terminates the current processing. The communication server101 repeats the processing of S30 again after a certain time haselapsed. If it is determined that the first setting time elapsed sincethe communication established section was set (S30: YES), the processingof the communication server 101 proceeds to S32.

In S32, the communication server 101 uses the section setting unit 13 torelease the communication established section. When the communicationestablished section is released, the communication server 101 completesthe release processing of the communication established section.

<Release Processing of a Communication Interrupted Section>

FIG. 4B is a flowchart showing the release processing of a communicationinterrupted section. The flowchart shown in FIG. 4B is executed when acommunication interrupted section was set.

In S40, the communication server 101 uses the section setting unit 13 todetermine whether the second setting time has elapsed since thecommunication interrupted section was set, as shown in FIG. 4B. If it isnot determined that the second setting time has elapsed since thecommunication interrupted section was set (S40: NO), the communicationserver 101 terminates the current processing. The communication server101 repeats the processing of S40 again after a certain time haselapsed. If it is determined that the second setting time has elapsedsince the communication interrupted section was set (S40: YES), theprocessing of the communication server 101 proceeds to S42.

In S42, the communication server 101 uses the section setting unit 13 torelease the communication interrupted section. After releasing thecommunication interrupted section, the communication server 101completes the release processing of the communication interruptedsection.

<Vehicle Control Performed by the Vehicle Control Device>

FIG. 5 is a flowchart showing vehicle control performed by the vehiclecontrol device. The flowchart shown in FIG. 5 is executed, for example,when a driver's operation to request to start the system driven controlis recognized.

As shown in FIG. 5, in S50, the ECU 30 of the vehicle control device 102uses the vehicle position recognition unit 31 to recognize the positionof the host vehicle on the map. The vehicle position recognition unit 31recognizes the position of the host vehicle on the map based on theposition information received by the GPS receiver 21 and the mapinformation stored in the vehicle side map database 25. After that, theprocessing of the ECU 30 proceeds to S52.

In S52, the ECU 30 uses the section information acquisition unit 34 toacquire the section information. The section information acquisitionunit 34 acquires the section information, which was set by the sectionsetting unit 13, via communication with the communication server 101.After that, the processing of the ECU 30 proceeds to S54.

In S54, the ECU 30 uses the section determination unit 36 to determinewhether the host vehicle is traveling in a communication establishedsection. The section determination unit 36 determines whether the hostvehicle is traveling in a communication established section, based onthe position of the host vehicle on the map and the section information.If it is determined that the host vehicle is traveling in acommunication established section (S54: YES), the processing of the ECU30 proceeds to S56. If it is not determined that the host vehicle istraveling in a communication established section (S54: NO), theprocessing of the ECU 30 proceeds to S58.

In S56, the ECU 30 uses the vehicle control unit 37 to perform thesystem driven control of the host vehicle. The vehicle control unit 37performs the system driven control of the host vehicle based on the mapinformation, the position of the host vehicle on the map, the roadconditions around the host vehicle, the traveling state of the hostvehicle, the road condition information acquired via communication withthe communication server 101, and the travel plan generated by thetravel plan generation unit 35. The vehicle control unit 37 causes thehost vehicle to travel by the system driven control in the communicationestablished section. After that, the ECU 30 terminates the currentprocessing and, after a predetermined time elapses, repeats theprocessing from S50 again. If the host vehicle is under the driverdriven control, the ECU 30 performs the system driven control afterobtaining permission from the driver.

In S58, the ECU 30 uses the section determination unit 36 to determinewhether the host vehicle is traveling in a communication interruptedsection. The section determination unit 36 determines whether the hostvehicle is traveling in an communication interrupted section, based onthe position of the host vehicle on the map and the section information.If it is determined that the host vehicle is traveling in acommunication interrupted section (S58: YES), the processing of the ECU30 proceeds to S60. If it is not determined that the host vehicle istraveling in a communication interrupted section (S58: NO), theprocessing of the ECU 30 proceeds to S62.

In S60, the ECU 30 uses the vehicle control unit 37 to perform thedriver driven control of the host vehicle. The vehicle control unit 37performs the driver driven control of the host vehicle based on thedriving operation of the driver, the road condition around the hostvehicle, and the traveling state of the host vehicle. The vehiclecontrol unit 37 causes the host vehicle to travel by the driver drivencontrol in the communication interrupted section. After that, the ECU 30terminates the current processing and, after a predetermined timeelapses, repeats the processing from S50 again. If the host vehicle isunder the system driven control, the ECU 30 executes the driver drivencontrol after alerting the driver.

In S62, the ECU 30 uses the vehicle control unit 37 to perform thedriver driven control of the host vehicle. The processing in S62 is thesame as that in S60 and, therefore, the description is omitted. Afterthat, the ECU 30 terminates the current processing and, after apredetermined time elapses, repeats the processing from S50 again.

<Vehicle Control Switching Restriction Processing>

FIG. 6 is a flowchart showing the vehicle control switching restrictionprocessing. The flowchart shown in FIG. 6 is executed, for example, whenthe vehicle control device 102 acquires the section information thatincludes the information on a communication established section. Theflowchart shown in FIG. 6 is executed for each communication establishedsection. The flowchart shown in FIG. 6 may also be executed when thehost vehicle enters a communication established section.

As shown in FIG. 6, the ECU 30 uses the section determination unit 36 todetermine whether the length of a communication established section isequal to or less than the set threshold value. If it is not determinedthat the length of the communication established section is equal to orless than the set threshold value (S70: NO), the ECU 30 terminates thecurrent processing. If it is determined that the length of thecommunication established section is equal to or less than the setthreshold (S70: YES), the processing of the ECU 30 proceeds to S72.

In S72, the ECU 30 uses the vehicle control unit 37 to set that thesystem driven control will not be performed in the communicationestablished section. After that, the ECU 30 terminates the currentprocessing. The vehicle control unit 37 does not perform the systemdriven control even when it is determined that the host vehicle istraveling in the communication established section.

[Effect of Vehicle Communication System]

The vehicle communication system 100 in this embodiment described abovesets a communication established section and a communication interruptedsection on the map based on the positions of the communicatingcommunication vehicles on the map. The vehicle communication systemperforms the system driven control of the host vehicle when the hostvehicle travels in a communication established section and, at the sametime, performs the driver driven control of the host vehicle when thehost vehicle travels in a communication interrupted section. In thisway, the vehicle communication system 100 performs vehicle controlappropriately according to the communication environment of a section inwhich the host vehicle travels.

The vehicle communication system 100 further sets a communicationvehicle absence section on the map based on the positions of thecommunicating communication vehicles on the map and, when the hostvehicle travels in a communication vehicle absence section, performs thedriver driven control. In this way, the vehicle communication system 100performs the vehicle control of the host vehicle appropriatelyconsidering a section in which there is no communication vehicle.

Furthermore, the vehicle communication system 100 does not perform thesystem driven control if the length of a communication establishedsection is equal to or less than the set threshold value because, inthis case, the system driven control can be executed only for a shortperiod of time and, immediately after the short period of time, thevehicle control is switched again to the driver driven control. Thisavoids the frequent switching of vehicle control.

Furthermore, considering that the communication environment of a sectionvaries with the elapse of time, the vehicle communication system 100releases the setting of a communication established section and acommunication interrupted section when a certain time has elapsed,allowing vehicle control to be performed appropriately according to theactual communication environment.

Although preferred embodiments of the present disclosure have beendescribed above, the present disclosure is not limited to theabove-described embodiments. The present disclosure can be implementednot only in the embodiments described above but also in various forms towhich various modifications and improvements are added based on theknowledge of those skilled in the art.

For example, the section setting unit 13 may set a communicationestablished section, a communication interrupted section, or acommunication vehicle absence section for each section that is set inadvance on the map. The sections that are set in advance may be formedby dividing a road into sections, one for each intersection or eachbranch point, or may be formed by dividing a road at fixed intervals.Any method may be used to form a section that is set in advance.

The section setting unit 13 may set the traveling range of communicationvehicles in communication with the communication server 101 as acommunication established section even if the communication with thecommunication server 101 does not continue for a predetermined time ormore. The section setting unit 13 does not necessarily have to release acommunication established section and/or a communication interruptedsection when a predetermined time elapses.

The section determination unit 36 may determine whether the host vehicleis to travel in a communication established section, based on theposition of the host vehicle on the map and the section information. Thesection determination unit 36 may determine whether the host vehicle isto travel in a communication interrupted section, based on the positionof the host vehicle on the map and the section information. The sectiondetermination unit 36 may also determine whether the host vehicle is totravel in a communication vehicle absence section, based on the positionof the host vehicle on the map and the section information.

The vehicle control device 102 does not necessarily have to include thevehicle side map database 25, but may acquire the map information, forexample, from the communication server 101. The vehicle control device102 may set a target route using a known navigation system instead ofthe travel plan generation unit 35.

If it is determined that the host vehicle is traveling in acommunication vehicle absence section, the vehicle control unit 37 neednot perform the driver driven control in the same way as when the hostvehicle is determined to be traveling in a communication interruptedsection. If it is determined that the host vehicle is traveling in acommunication vehicle absence section, the vehicle control unit 37 mayperform the system driven control specifically provided for acommunication vehicle absence section while the communication betweenthe communication server 101 and the host vehicle is established.

Furthermore, even if the length of a communication established sectionin which the host vehicle travels not under the system driven control isequal to or smaller than the set threshold, the vehicle control unit 37may perform the system driven control in that communication establishedsection.

The system driven control for a communication vehicle absence section isautonomous driving control with an assistance level lower than that ofthe system driven control that is performed when it is determined thatthe host vehicle is traveling in a communication established section.The system driven control for a communication vehicle absence section isthought of as vehicle control with a smaller upper limit of the vehiclespeed and/or a smaller upper limit of the amount of change in thesteering angle of the host vehicle (temporal differentiation of steeringangle) than that in the system driven control for a communicationestablished section. The system driven control for a communicationestablished section may be considered as control corresponding toautonomous driving level 4, and the system driven control for acommunication vehicle absence section as control corresponding toautonomous driving level 3. When the communication between thecommunication server 101 and the host vehicle is interrupted for apredetermined time or more, the vehicle control unit 37 notifies thedriver about the interruption and, then, switches the system drivencontrol for a communication vehicle absence section to the driver drivencontrol.

In addition, the vehicle control unit 37 may be configured in the modedescribed below with consideration for preventive safety services. Thatis, the vehicle control unit 37 may perform warning control if it isdetermined that the host vehicle is traveling in a communicationestablished section, may perform alerting control if it is determinedthat the host vehicle is traveling in a communication vehicle absencesection, and may cause the driver to perform the manual driving if it isdetermined that the host vehicle is traveling in a communicationinterrupted section. In this configuration, when a communicationestablished section becomes a communication vehicle absence section asthe time elapses, the server side map database 14 may still store theobstacle information on a static obstacle (such as a falling object),which was recognized when the section was a communication establishedsession, even after the section has become a communication vehicleabsence section. This means that, when it is determined that the hostvehicle is traveling in a communication vehicle absence section, thevehicle control unit 37 can perform alerting control using the obstacleinformation on a static obstacle that was recognized when the sectionwas a communication established section. That is, if it is determinedthat the host vehicle is traveling in a communication vehicle absencesection and if there is obstacle information on a static obstacle thathas been held, the vehicle control unit 37 can perform alerting controlthat alerts the driver to the static obstacle, thus improving thequality of preventive safety services. For the obstacle information on adynamic obstacle such as a pedestrian, the server side map database 14discards the obstacle information when a communication establishedsection becomes a communication vehicle absence section when as the timeelapses. As a result, this mode can contribute to improving the qualityof preventive safety services while saving the amount of data smallerthan that in the mode when the obstacle information on all obstacles isheld.

What is claimed is:
 1. A vehicle communication system comprising: acommunication server configured to communicate with a plurality ofcommunication vehicles, the communication vehicles being vehiclesconfigured to communicate with the communication server, thecommunication server configured to: recognize positions of communicatingcommunication vehicles on a map via communication with the communicationvehicles, the communicating communication vehicles being included in theplurality of communication vehicles and being in communication with thecommunication server, and set a communication established section and acommunication interrupted section on the map, based on the positions ofthe communicating communication vehicles on the map; and a vehiclecontrol device configured to communicate with the communication serverand configured to perform vehicle control of a host vehicle using anactuator mounted on the host vehicle, the vehicle control deviceincluding at least one electronic control unit configured to recognize aposition of the host vehicle on the map, acquire section information onthe communication established section and the communication interruptedsection, determine in which section, either the communicationestablished section or the communication interrupted section, the hostvehicle is traveling, based on the position of the host vehicle on themap and the section information, and perform system driven control ofthe host vehicle when the host vehicle travels in the determinedcommunication established section, and perform driver driven control ofthe host vehicle when the host vehicle travels in the determinedcommunication interrupted section.
 2. The vehicle communication systemaccording to claim 1, wherein the at least one electronic control unitis configured to set, as the communication established section, asection in which a communication vehicle of the plurality ofcommunication vehicles that have continued communication with thecommunication server for a predetermined time or more are traveling,based on the positions of the communicating communication vehicles onthe map, and set, as the communication interrupted section, a section inwhich a certain number or more of communication vehicles of theplurality of communication vehicles have communication interrupted,based on the positions of the communicating communication vehicles onthe map.
 3. The vehicle communication system according to claim 1,wherein the at least one electronic control unit is configured to setthe communication established section, the communication interruptedsection, and a communication vehicle absence section on the map based onthe positions of the communicating communication vehicles on the map,the at least one electronic control unit is configured to acquire thesection information on the communication established section, thecommunication interrupted section, and the communication vehicle absencesection that are set on the map, the at least one electronic controlunit is configured to determine which of the communication establishedsection, the communication interrupted section, or the communicationvehicle absence section is a section in which, the host vehicle istraveling, based on the position of the host vehicle on the map and thesection information, and the at least one electronic control unit isconfigured to perform the driver driven control when the host vehicletravels in the communication vehicle absence section.
 4. The vehiclecommunication system according to claim 3, wherein the at least oneelectronic control unit is configured to set, as the communicationvehicle absence section, a section in which there is no communicatingcommunication vehicle, based on the positions of the communicationvehicles on the map.
 5. The vehicle communication system according toclaim 1, wherein the at least one electronic control unit is configurednot to perform the system driven control in the determined communicationestablished section when a length of the determined communicationestablished section in which the host vehicle not performing the systemdriven control travels is equal to or less than a threshold value. 6.The vehicle communication system according to claim 1, wherein the atleast one electronic control unit is configured to release a setting ofthe communication established section when a first setting time haselapsed since the communication established section was set on the map,and release a setting of the communication interrupted section when asecond setting time has elapsed since the communication interruptedsection was set on the map.
 7. The vehicle communication systemaccording to claim 6, wherein the first setting time is 30 seconds ormore and 1 minute or less, and the second setting time is 30 seconds ormore and 3 minutes or less.
 8. The vehicle communication systemaccording to claim 1, wherein the at least one electronic control unitis configured to generate a travel plan including candidates of aplurality of routes on which the host vehicle will travel beforearriving at a destination, based on the position of the host vehicle onthe map and the section information.
 9. The vehicle communication systemaccording to claim 8, wherein the at least one electronic control unitis configured to determine, from the candidates of the routes, atraveling route on which the host vehicle will travel based on thesection information.
 10. The vehicle communication system according toclaim 9, wherein the at least one electronic control unit is configuredto determine, from the candidates of the routes, a route including amaximum number of the communication established sections as a travelingroute cin which the host vehicle will travel, based on the sectioninformation.
 11. The vehicle communication system according to claim 1,wherein the system driven control is traveling control under which thevehicle control device performs acceleration, deceleration, and steeringof the host vehicle autonomously, and the driver driven control istraveling control under which the host vehicle travels based on adriving operation of a driver of the host vehicle.
 12. The vehiclecommunication system according to claim 1, wherein the communicationserver is configured to communicate road condition information with theplurality of communication vehicles, and the host vehicle is configuredto acquire the road condition information from the communication server,and the at least one electronic control unit is configured to performthe system driven control of the host vehicle based on the roadcondition information when the host vehicle travels in the determinedcommunication established section.
 13. A vehicle control devicecomprising: at least one electronic control unit configured to:recognize a position of a host vehicle on a map; acquire sectioninformation on a communication established section and a communicationinterrupted section via communication with a communication serverconfigured to communicate with a plurality of communication vehicles,the communication vehicles being vehicles configured to communicate withthe communication server, the communication established section and thecommunication interrupted section being set on the map by thecommunication server based on a status of communication with thecommunication vehicles; determine in which section, either thecommunication established section or the communication interruptedsection, the host vehicle is traveling, based on the position of thehost vehicle on the map and the section information; perform vehiclecontrol of the host vehicle using an actuator mounted on the hostvehicle, in such a way that system driven control of the host vehicle isperformed, when the host vehicle travels in the determined communicationestablished section; and perform driver driven control of the hostvehicle when the host vehicle travels in the determined communicationinterrupted section.
 14. The vehicle control device according to claim13, wherein the communication server is configured to communicate roadcondition information with the plurality of communication vehicles, andthe at least one electronic control unit is configured to perform thevehicle control of the host vehicle using the actuator mounted on thehost vehicle, in such a way that the system driven control of the hostvehicle is performed based on the road condition information acquiredfrom the communication server, when the host vehicle travels in thedetermined communication established section.
 15. A vehiclecommunication system comprising: a communication server configured tocommunicate with a plurality of communication vehicles, thecommunication vehicles being vehicles configured to communicate with thecommunication server, the communication server being configured to:recognize positions of communicating communication vehicles on a map viacommunication with the communication vehicles, the communicatingcommunication vehicles being included in the plurality of communicationvehicles and being in communication with the communication server, andset a communication established section and a communication interruptedsection on the map, based on the positions of the communicatingcommunication vehicles on the map; and a vehicle control deviceconfigured to communicate with the communication server and configuredto perform vehicle control of a host vehicle using an actuator mountedon the host vehicle, the vehicle control device including at least oneelectronic control unit configured to recognize a position of the hostvehicle on the map, to acquire section information on the communicationestablished section and the communication interrupted section, todetermine in which section, either the communication established sectionor the communication interrupted section, the host vehicle is traveling,based on the position of the host vehicle on the map and the sectioninformation, to perform a driving assistance when the host vehicletravels in the determined communication interrupted section, and toperform high-level driving assistance, the high-level driving assistancehaving a higher level of intervention in driving control of the vehiclecontrol device than the driving assistance, when the host vehicletravels in the determined communication established section.
 16. Thevehicle communication system according to claim 15, wherein thecommunication server is further configured to communicate road conditioninformation with the plurality of communication vehicles, and the hostvehicle is configured to acquire the road condition information from thecommunication service, and the at least one electronic control unit isfurther configured to perform the high-level driving assistance based onthe road condition information when the host vehicle travels in thedetermined communication established section.